Question about verticles!(new on blender)
If I understand correctly, your main question is what the difference is between smoothing an object via a subdivision surface modifier and via smooth shading.

A subdivision surface modifier smooths an object by taking each face and dividing it into smaller faces, and then smooths the result. You aren't able to edit the vertices generated by the modifier without applying it. However, you are able to edit the original faces still, and the modifier will update accordingly.

Smooth shading doesn't actually change the vertices of your object. What smooth shading does is tell blender to reflect light off of the surfaces as if they were smooth. If you take a default sphere and set the shading to smooth, all it does is tell blender to reflect light off of the object as if it was a perfect sphere and not made up of flat faces.

Often both a modifier and smooth shading are used together, although not always.

With blender, you can almost always edit the vertices of your object with no problems. There are a few cases where it's not a good idea or not easy to edit them, but they are scenarios you won't encounter for a while.